Flotation machine



Feb. 28, 1933.

J. P. RUTH, JR

FLOTATION MACHINE Filed March 11, 1929 3mm yaw/7% 2 Zzzf Cutout:

Patented Feb. 28, 1933 UNITED STATES PATENT OFFICE JOSEP'R P. RUTH, JR, OF DENVER, COLORADO, ASSIGNOR TO THE RUTH COMPANY, OF DENVER, COLORADO, A CORPORATION OF COLORADO FLOTATION MACHINE Application filed March 11, 1929. Serial No. 345,972.

This invention relates to improvements in flotation machines of the type employed for the purpose of separating mineral values from ore ulp.

In mac ines of the type to which this invention relates-an impeller is employed for the purpose of agitatingthe pulp and introducing the air thereinto so as to produce the necessary froth for effecting the desired separation. The impeller is located, as a rule, near the bottom of the machine and when the machine is in operation thecentrifugal force produced by this impeller raises the level of the liquid in the frothing chamber to a point above that in the intake chamber and thus produces a hydrostatic head that tends toreturn the pulp to the intake chamber of the machine. This hydrostatic head, together with other forces that are active when the machine is in operation, tends to produce a local circulation of air about the impeller in a manner which will be hereinafter more clearly described, and this local circulation decreases the capacity of the machine and increases the power consumption per unit of pulp acted 7 upon, thereby increasing the cost and slowing down the operation.

It is the object of this invention to produce an improved machine of the type referred to which shall be so constructed that there will be no appreciable leakage about the impeller and which can therefore be more cheaply operated and have a greater capacity than ordinary machines bf this type. The above and other objects which may be come apparent as the description proceeds are attained by means of a construction and an arrangement of parts which will now be described, reference for this purpose being had to the accompanying drawing in which the preferred embodiment thereof has been illustrated, and in which: Fig. 1 is a front elevation of one of the improved flotation machines to which this invention relates; Fig. 2 is a vertical section taken on line 2-2, Fig. 1; and

Fig. 3 is a fragmentary section through a portion of the impeller and a part of the adjacent casing showing the seal between the movable surfaces.

In the drawing reference numeral 1 represents the feed compartment of the machine, into which the pulp that is to be treated is delivered, and 2 represents the frothing compartment. Locatedwithin the feed compartment is an impeller housing whose bottom has been designated by reference numeral 3 and whose top has been designated by refer-Q ence numeral 4. The bottom 3 has a downwardly concave conical upper surface and thetop 4 has itslower surface conically convex. The upper or cover member 4 has a central opening 5, whose wall is formed by a downwardly extending flange 6 that is surrounded by air annular surface 7 lying in'a horizontal plane. Located within the opening'of the impeller housing is an impeller 8 which is secured to the lower end of the impeller 7 shaft 9. This shaft is mounted for rotation,

in vertically spaced bearings 10 and 11 that are connected with the frame work of the machine. Secured to the upper end of shaft 9 is a grooved pulley 12 which is connected 7 by means of belts 13 with the grooved pulley 14 on the drive shaft of motor 15. The impeller is provided with radial openings 16 and fan blades 17 and is so constructed that there is an annular recess between the hub 18 and that part of the impeller in which the openings 16 are located so that the pulp that.

is fed into the chamber 1 has a free passage into the interior of the impeller. When the motor is in operation and the shaft 9 rotates 35 at a high velocity, the impeller will act in the manner of a centrifugal pump and suck the pulp downwardly through the opening 5 and deliver it to the frothing chamber. As the capacity of the impeller is greater on than the amount of pulp delivered to the feed chamber, a large amount of air will be sucked in through the opening 5 and will be mixed with the pulp and will form bubbles that rise upwardly in the frothing chamber and these bubbles attach to themselves the mineral values in the manner well understood. Since water is almost one thousand times heavier than air it isevident that if the impeller is run at a speed sufiicient to deliver water 101 against a certain hydrostatic head it will not deliver air at suflicient pressure to overcome this head and therefore it is necessary to provide special means for getting the air out of 5 the openings 16 and this means comprises the blades 17 which extend beyond the outer ends of the openings and therefore when the impeller rotates the water will leave the rear sides of the blades, thereby producing a. cav- ,ity which will fill with air and this air will then pass upwardly and outwardly, due to its light weight and to the action of. the water with which it is surrounded. The blades 17 therefore constitute means carried by the propeller for forcing the air into the liquid stream against the hydrostatic head. The dotted line 19 designates the liquid level in the frothing chamber and the pulp flowsiupwardly through the passage 20 and over the upper curved top 21 of the partition wall 22 and into the launder 23. The pulp flows over the discharge lip 24 and into the chute 25 and thence into the launder 26 which conducts it to the place desired. As this invention does not concern itself with the exact construction of the machine, as a whole, but has reference more particularly to the impeller and the parts associated therewith, the other parts of the machine, will not be described in detail, but the description will be limited to the impeller and to the means employed for producing a seal between the impeller and the underside of member 4 for the purpose of preventing local circulation of the pulp. The impeller housing comprism members 3 and 4 rests upon the bottom 0 the feed chamber and theupper surface of member 4 is provided with an upwardly extending cylindrical flange 27 at whose lower en the gasket 28 is located. A ring 29 which may e formed of metal rests upon the gasket 28 and is forced downwardly against the gasket by the action of the clamps 30 and bolts 31. This gasket forms a seal that prevents the pulp from flowing downwardly about the outside of flange 27.' I have already called attention to the annular surface 7 that surrounds the flange 6 and I will now call attention to the fact that the impeller is rovided with an annular surface 32 that is a apted to fit against the surface 7 and to be held in close proximity to the latter during the operation of the machine so as to prevent pulp from flowing between these two surfaces in the direction of the arrows in Fig. 3. Surfaces 7 and 32 are maintained in the desired adjacent position by the shaft 9 which is adjustable in the direction of its length so that surfaces 7 and 32 may be moved towards or away from each other for the purpose of obtaining the desired sealing effect. From Fig. 2 it will be seen that the upper end of shaft 9 is provided witha central opening which is threaded for the reception of the threaded end of bolt 33. A cap 34 surrounds the upper end of shaft 9 and has its lower edge resting on the upper end of the hub 35 of pulley 12. The lower end of this hub is separated from the upper end of bearing 11 bymeans of a ball bearing 36. The bolt 33 extends through the upper end of shaft 34 and is provided with a nut 37. When this nut is turnedon the bolt 33, the shaft will be raised or lowered in its bearing, depending on the direction in which the nut is rotated. Since the shaft must slide through hub 35, it must be so connected to the latter that it is free to move longitudinally and it must also be held against relative rotation, and this connection is preferably accomplished by means of grooves and a spline in the usual manner. Attention is called to the flange 6 about which the annular surface -7 extends. This flange extendsdownwardly to approximately the level of the upper walls of openings 16 and serves to deflect any leakage downwardly and to direct it into the outwardly moving stream of pplp in ,the manner indicated by the arrow.

hen the parts are first assembled and when the machine is new, surfaces 7 and 32 are rarely, if ever, parallel, and therefore when the machine is first put into operation, more or less leakage will take place between these surfaces, but, after the machine has been in use for some time, the surface 7 will be worn at its lowest point and this gradual 'wear will soon bring it into parallel relation with the rotating surface 32. During this period when the surface 7 is wearing the nut 37 must be quite frequently adjusted so as to compensate for the wear and so as to bring the surface 32 into sufliciently close proximity to surface 7 to bring about the necessary wear for the purpose of making the surface 7 parallel with the rotating surface 32. After these two surfaces have been worn so as to become absolutely parallel, they are adjusted so as to reduce the leakage to a minimum while still permitting the impeller to rotate freely. It is, of course, necessary to adjust the relative positions of these surfaces from time to time as more or lesswear is continually taking place and for this purpose the surfaces are also formed on elevated portions so as to provide material for considerable wear.

When the machine is in operation, the impeller rotates at a high speed and the pulp flows through the impeller in the direction of the arrows in Fig. 3. If any leakage occurs between the surfaces 7 and 32, a local circulation of air is set up, and this is detrimental to the operation of the machine as it decreases the capacity and increases the amount of power necessary for treating a given amount of ore. It is'very diflicult to absolutely prevent leakage at this point, but by means of the construction shown and described, this leakage can be limited to such an extent that its effect is practically negligible. l From the above description it will be apparent that I have produced a very simple construction by means of which the air leak age between the impeller and the impeller housing of a flotation machine can be main- 5 tained at such a small value. as to be practically negligible and which, therefore, produces a machine which hasa greater capacity for unit consumption of energy than machines of this type which permitlocal circulation of pulp about the impeller.

Having described the invention whalt 1s claimed as new is:

1. Means for aerating pulp comprising, a rotatable closed impeller having an intake opening adjacent its center of rotation for the admission of air and pulp, means carried by the impeller for producing low pressure cavities along the periphery of the impeller for aiding the movement of air and a and the intake opening 'folapreventing the air from returning to the in e.

2. In a flotation machine having a reoeiv-' ing conduit for pulp and a frothing compartment for the reception of aerated pulp, an impeller housing located underneath the receiving conduit, the upper wall of the housing having an opening through which pulp may flow into the interior thereof, the housing having a discharge opening in communication .with the bottom of the frothingchamber, a rotatable impeller located in the housing, the upper surface -of the impeller having an openin surrounded by a flat annular sealing sur ace, the edge of the opening in the upper wall of the housing terminating in a downwardly extending circular flange that extends into the opening in the impeller, the under surface of the housing having an annular sealing surface immediately surrounding theflange, means for rotatably supporting the impeller, means for adjusting the position of the sealing surfaces with respect to each other, and means comprising blades extending outwardly from the impeller for producing low pressure cavities for the accumulation ofair.

3. A flotation machine for use in aerating pulp and for raising the aerated pulp from a lower to a higher level comprising, in combination, a support havingtwoalignedbearings one above the other and arranged with their axes vertical, a shaft mounted for rotation in the bearings, a housing secured to the support at apoint below the lowermost bearing, the interior of said housing forming an impeller chamber, the upper wall of the housing having an opening and a circular flange surrounding the opening and extending downwardly into the impeller chamber, the under surface of the said upper wall having a flat annular surface substantially concentric with the flan e, an impeller secured to the lower end of t e shaft and located within the 35 impeller housing, the upper surface of the seal between the periphery of theimpeller.

impeller having an annular opening into which the circular flange extends and an annular flat surface that is adapted to cooperate with the annular surface on the underside of the upper wall of the chamber to form a seal, a thrust bearing supported on the upper of the two aligned bearings, and means associated with the upper end of the shaft for moving it upwardly whereby the annular surface on the impeller can be adjusted with respect to the annular surface on the lower surface of the impeller housing to compensate for wear, there being a receiving compartment located above the upper wall of the impeller housing and a frothing chamber in communication with the discharge of the impeller.

4. Means for aerating pulp, comprising, a rotatable impeller having an opening adjacent its center of rotation for the admission of air and pulp, means carried by the impeller for producing low pressure cavities along the periphery of the impeller for aiding the movement of air, and a seal between the aerated pulp compartment and the central opening, said seal comprising an annular stationary portion in close proximity to an annular surface of the rotatable impeller.

5. Means for aerating pulp, comprising, in

combination, a tank for the aeratedpulp, a' 

